Funny you ask, I was looking for the board to measure it - and then I realized I could just count the pixels!
I made the photo by scanning the board on my Brother MFC with a 1200 DPI scanner. The image is just shy of 6000x6000 pixels, so that makes the board about 5" square.
Around the same time I bought that core plane, I bought a bag of bits from someone in eastern Europe: a little ziplock bag with about 512 loose ferrite cores of this same size. Yep, that's 64 bytes in a baggie! It is pretty cool to see loose bits like that.
But if you think these bits are tiny, they got a lot smaller when they went to machine weaving. Maybe half or quarter this size.
Of course, "tiny" is relative, isn't it? At least you can see these bits, not like your newfangled semiconductor memory.
I made the photo by scanning the board on my Brother MFC with a 1200 DPI scanner. The image is just shy of 6000x6000 pixels, so that makes the board about 5" square.